Well it has more to do with warrenty then anything else.
All parts are made by the same manufactures, they are rated by how well they meet specs. The parts are than sold to whichever brandname or generic company, that pays the price. It's in the area of warrenty where the brand-
name wins out over generic. If you treat your machine nice it should work okay, the only difference would be length of time before breakdown. Possibley in the speed of operation. Building your own works only if you have the money, time, and knowledge to do it right. And that's the way it is.
Do you prefer brand-name or generic computers?
Brand name (tell us why)
Generic (tell us why)
Either one, makes no difference
None, I prefer the ones I build myself (tell us why)

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